But aren't they family now?

Wedding reveling for the Duke and Duchess of Cambridge is still going on, but Facebook fans want to see another royal hook-up -- their siblings!

The group page "Pippa Middleton is single -- Prince Harry likes this," is devoted to the possibility of Prince William's best man, 26, courting Princess Catherine's little sis, 27.

Just hours after the royal wedding Friday, the group had more than 30,000 members, whose wall posts ranged from the sweet -- "They make a fantastic couple" -- to the vulgar.

While Harry is still linked to on-again-off-again girlfriend Chelsy Davy (who attended the wedding), the Facebook fans might not be that far off; during the ceremony, Harry spent much of his time by Pippa's side and even managed to make the maid of honor laugh.

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